Responses of seedlings of tropical woody plants to environmental stresses with emphasis on Theobroma cacao and Hevea brasiliensis

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6991443

Sena Gomes, A R

Relative humidity, flooding, temperature, wind, and SO/sub 2/ variously influenced physiological processes and growth of tropical woody plants, with emphasis on three Theobroma cacao varieties and three Hevea brasiliensis families. Stomata were smaller and more numerous in Theobroma than in Hevea. In Theobroma, but not Heavea, stomatal frequency decreased from the leaf base to the apex and from the midrib outward. Stomata of Theobroma cacao var. Catongo opened in high relative humidity (RH) and closed in low RH. The more open stomata in high RH were associated with high rates of photosynthesis, low leaf water potential, high water use efficiency (WUE), and low transpiration rate (TR). Variations in TR and WUE were correlated with changes in vapor pressure deficit. Other responses included stomatal closure, decreased chlorophyll content, leaf epinasty, production of hypertrophied lenticels and adventitious roots, and acceleration of ethylene production. Responses to flooding varied with species, Theobroma varieties and Hevea families. Effects of temperature regimes on growth varied with species, varieties and families, plant parts, growth parameters, and time of harvesting. Optimal temperatures for dry weight increase of stems or roots of Theobroma cacao var. Comum were 22.2 C; and 33.3 C for dry weight increase or relative growth rates of leaves or seedlings. Optimal temperatures for growth varied for Hevea families. Wind injured leaves of Theobroma cacao, with more injury by wind of 6.0 than 3.0 m s/sup -1/. Stomata were more open on windy than on calm days, but tended to close at high wind speeds. Wind lowered transpiration rate but the reduction was not correlated with leaf dehydration. SO/sub 2/ at 0.5, 1.0, or 1.5 ppm for 24 h did not injure Theobroma leaves but reduced dry weight increment of leaves of var. Catongo but not Catongo/Sial.

• Research Organization: Wisconsin Univ., Madison (USA)
• OSTI ID: 6991443
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL STRESS
BIOLOGICAL EFFECTS
CACAO TREES
SEEDLINGS
HEVEA
SULFUR DIOXIDE
TOXICITY
CHLOROPHYLL
FLOODS
HUMIDITY
INJURIES
LEAVES
PHOTOSYNTHESIS
PHYSIOLOGY
PLANT GROWTH
ROOTS
STOMATA
TEMPERATURE EFFECTS
TRANSPIRATION
TROPICAL REGIONS
WATER VAPOR
WIND
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
DISASTERS
EUPHORBIA
FLUIDS
GASES
GROWTH
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
OPENINGS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHYTOCHROMES
PIGMENTS
PLANTS
PORPHYRINS
PROTEINS
SULFUR COMPOUNDS
SULFUR OXIDES
SYNTHESIS
TREES
VAPORS
560300* - Chemicals Metabolism & Toxicology